1 /* pngerror.c - stub functions for i/o and memory allocation 2 * 3 * Last changed in libpng 1.6.1 [March 28, 2013] 4 * Copyright (c) 1998-2013 Glenn Randers-Pehrson 5 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) 6 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) 7 * 8 * This code is released under the libpng license. 9 * For conditions of distribution and use, see the disclaimer 10 * and license in png.h 11 * 12 * This file provides a location for all error handling. Users who 13 * need special error handling are expected to write replacement functions 14 * and use png_set_error_fn() to use those functions. See the instructions 15 * at each function. 16 */ 17 18 #include "pngpriv.h" 19 20 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) 21 22 static PNG_FUNCTION(void, png_default_error,PNGARG((png_const_structrp png_ptr, 23 png_const_charp error_message)),PNG_NORETURN); 24 25 #ifdef PNG_WARNINGS_SUPPORTED 26 static void /* PRIVATE */ 27 png_default_warning PNGARG((png_const_structrp png_ptr, 28 png_const_charp warning_message)); 29 #endif /* PNG_WARNINGS_SUPPORTED */ 30 31 /* This function is called whenever there is a fatal error. This function 32 * should not be changed. If there is a need to handle errors differently, 33 * you should supply a replacement error function and use png_set_error_fn() 34 * to replace the error function at run-time. 35 */ 36 #ifdef PNG_ERROR_TEXT_SUPPORTED 37 PNG_FUNCTION(void,PNGAPI 38 png_error,(png_const_structrp png_ptr, png_const_charp error_message), 39 PNG_NORETURN) 40 { 41 #ifdef PNG_ERROR_NUMBERS_SUPPORTED 42 char msg[16]; 43 if (png_ptr != NULL) 44 { 45 if (png_ptr->flags& 46 (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) 47 { 48 if (*error_message == PNG_LITERAL_SHARP) 49 { 50 /* Strip "#nnnn " from beginning of error message. */ 51 int offset; 52 for (offset = 1; offset<15; offset++) 53 if (error_message[offset] == ' ') 54 break; 55 56 if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT) 57 { 58 int i; 59 for (i = 0; i < offset - 1; i++) 60 msg[i] = error_message[i + 1]; 61 msg[i - 1] = '\0'; 62 error_message = msg; 63 } 64 65 else 66 error_message += offset; 67 } 68 69 else 70 { 71 if (png_ptr->flags&PNG_FLAG_STRIP_ERROR_TEXT) 72 { 73 msg[0] = '0'; 74 msg[1] = '\0'; 75 error_message = msg; 76 } 77 } 78 } 79 } 80 #endif 81 if (png_ptr != NULL && png_ptr->error_fn != NULL) 82 (*(png_ptr->error_fn))(png_constcast(png_structrp,png_ptr), 83 error_message); 84 85 /* If the custom handler doesn't exist, or if it returns, 86 use the default handler, which will not return. */ 87 png_default_error(png_ptr, error_message); 88 } 89 #else 90 PNG_FUNCTION(void,PNGAPI 91 png_err,(png_const_structrp png_ptr),PNG_NORETURN) 92 { 93 /* Prior to 1.5.2 the error_fn received a NULL pointer, expressed 94 * erroneously as '\0', instead of the empty string "". This was 95 * apparently an error, introduced in libpng-1.2.20, and png_default_error 96 * will crash in this case. 97 */ 98 if (png_ptr != NULL && png_ptr->error_fn != NULL) 99 (*(png_ptr->error_fn))(png_constcast(png_structrp,png_ptr), ""); 100 101 /* If the custom handler doesn't exist, or if it returns, 102 use the default handler, which will not return. */ 103 png_default_error(png_ptr, ""); 104 } 105 #endif /* PNG_ERROR_TEXT_SUPPORTED */ 106 107 /* Utility to safely appends strings to a buffer. This never errors out so 108 * error checking is not required in the caller. 109 */ 110 size_t 111 png_safecat(png_charp buffer, size_t bufsize, size_t pos, 112 png_const_charp string) 113 { 114 if (buffer != NULL && pos < bufsize) 115 { 116 if (string != NULL) 117 while (*string != '\0' && pos < bufsize-1) 118 buffer[pos++] = *string++; 119 120 buffer[pos] = '\0'; 121 } 122 123 return pos; 124 } 125 126 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_TIME_RFC1123_SUPPORTED) 127 /* Utility to dump an unsigned value into a buffer, given a start pointer and 128 * and end pointer (which should point just *beyond* the end of the buffer!) 129 * Returns the pointer to the start of the formatted string. 130 */ 131 png_charp 132 png_format_number(png_const_charp start, png_charp end, int format, 133 png_alloc_size_t number) 134 { 135 int count = 0; /* number of digits output */ 136 int mincount = 1; /* minimum number required */ 137 int output = 0; /* digit output (for the fixed point format) */ 138 139 *--end = '\0'; 140 141 /* This is written so that the loop always runs at least once, even with 142 * number zero. 143 */ 144 while (end > start && (number != 0 || count < mincount)) 145 { 146 147 static const char digits[] = "0123456789ABCDEF"; 148 149 switch (format) 150 { 151 case PNG_NUMBER_FORMAT_fixed: 152 /* Needs five digits (the fraction) */ 153 mincount = 5; 154 if (output || number % 10 != 0) 155 { 156 *--end = digits[number % 10]; 157 output = 1; 158 } 159 number /= 10; 160 break; 161 162 case PNG_NUMBER_FORMAT_02u: 163 /* Expects at least 2 digits. */ 164 mincount = 2; 165 /* FALL THROUGH */ 166 167 case PNG_NUMBER_FORMAT_u: 168 *--end = digits[number % 10]; 169 number /= 10; 170 break; 171 172 case PNG_NUMBER_FORMAT_02x: 173 /* This format expects at least two digits */ 174 mincount = 2; 175 /* FALL THROUGH */ 176 177 case PNG_NUMBER_FORMAT_x: 178 *--end = digits[number & 0xf]; 179 number >>= 4; 180 break; 181 182 default: /* an error */ 183 number = 0; 184 break; 185 } 186 187 /* Keep track of the number of digits added */ 188 ++count; 189 190 /* Float a fixed number here: */ 191 if (format == PNG_NUMBER_FORMAT_fixed) if (count == 5) if (end > start) 192 { 193 /* End of the fraction, but maybe nothing was output? In that case 194 * drop the decimal point. If the number is a true zero handle that 195 * here. 196 */ 197 if (output) 198 *--end = '.'; 199 else if (number == 0) /* and !output */ 200 *--end = '0'; 201 } 202 } 203 204 return end; 205 } 206 #endif 207 208 #ifdef PNG_WARNINGS_SUPPORTED 209 /* This function is called whenever there is a non-fatal error. This function 210 * should not be changed. If there is a need to handle warnings differently, 211 * you should supply a replacement warning function and use 212 * png_set_error_fn() to replace the warning function at run-time. 213 */ 214 void PNGAPI 215 png_warning(png_const_structrp png_ptr, png_const_charp warning_message) 216 { 217 int offset = 0; 218 if (png_ptr != NULL) 219 { 220 #ifdef PNG_ERROR_NUMBERS_SUPPORTED 221 if (png_ptr->flags& 222 (PNG_FLAG_STRIP_ERROR_NUMBERS|PNG_FLAG_STRIP_ERROR_TEXT)) 223 #endif 224 { 225 if (*warning_message == PNG_LITERAL_SHARP) 226 { 227 for (offset = 1; offset < 15; offset++) 228 if (warning_message[offset] == ' ') 229 break; 230 } 231 } 232 } 233 if (png_ptr != NULL && png_ptr->warning_fn != NULL) 234 (*(png_ptr->warning_fn))(png_constcast(png_structrp,png_ptr), 235 warning_message + offset); 236 else 237 png_default_warning(png_ptr, warning_message + offset); 238 } 239 240 /* These functions support 'formatted' warning messages with up to 241 * PNG_WARNING_PARAMETER_COUNT parameters. In the format string the parameter 242 * is introduced by @<number>, where 'number' starts at 1. This follows the 243 * standard established by X/Open for internationalizable error messages. 244 */ 245 void 246 png_warning_parameter(png_warning_parameters p, int number, 247 png_const_charp string) 248 { 249 if (number > 0 && number <= PNG_WARNING_PARAMETER_COUNT) 250 (void)png_safecat(p[number-1], (sizeof p[number-1]), 0, string); 251 } 252 253 void 254 png_warning_parameter_unsigned(png_warning_parameters p, int number, int format, 255 png_alloc_size_t value) 256 { 257 char buffer[PNG_NUMBER_BUFFER_SIZE]; 258 png_warning_parameter(p, number, PNG_FORMAT_NUMBER(buffer, format, value)); 259 } 260 261 void 262 png_warning_parameter_signed(png_warning_parameters p, int number, int format, 263 png_int_32 value) 264 { 265 png_alloc_size_t u; 266 png_charp str; 267 char buffer[PNG_NUMBER_BUFFER_SIZE]; 268 269 /* Avoid overflow by doing the negate in a png_alloc_size_t: */ 270 u = (png_alloc_size_t)value; 271 if (value < 0) 272 u = ~u + 1; 273 274 str = PNG_FORMAT_NUMBER(buffer, format, u); 275 276 if (value < 0 && str > buffer) 277 *--str = '-'; 278 279 png_warning_parameter(p, number, str); 280 } 281 282 void 283 png_formatted_warning(png_const_structrp png_ptr, png_warning_parameters p, 284 png_const_charp message) 285 { 286 /* The internal buffer is just 192 bytes - enough for all our messages, 287 * overflow doesn't happen because this code checks! If someone figures 288 * out how to send us a message longer than 192 bytes, all that will 289 * happen is that the message will be truncated appropriately. 290 */ 291 size_t i = 0; /* Index in the msg[] buffer: */ 292 char msg[192]; 293 294 /* Each iteration through the following loop writes at most one character 295 * to msg[i++] then returns here to validate that there is still space for 296 * the trailing '\0'. It may (in the case of a parameter) read more than 297 * one character from message[]; it must check for '\0' and continue to the 298 * test if it finds the end of string. 299 */ 300 while (i<(sizeof msg)-1 && *message != '\0') 301 { 302 /* '@' at end of string is now just printed (previously it was skipped); 303 * it is an error in the calling code to terminate the string with @. 304 */ 305 if (p != NULL && *message == '@' && message[1] != '\0') 306 { 307 int parameter_char = *++message; /* Consume the '@' */ 308 static const char valid_parameters[] = "123456789"; 309 int parameter = 0; 310 311 /* Search for the parameter digit, the index in the string is the 312 * parameter to use. 313 */ 314 while (valid_parameters[parameter] != parameter_char && 315 valid_parameters[parameter] != '\0') 316 ++parameter; 317 318 /* If the parameter digit is out of range it will just get printed. */ 319 if (parameter < PNG_WARNING_PARAMETER_COUNT) 320 { 321 /* Append this parameter */ 322 png_const_charp parm = p[parameter]; 323 png_const_charp pend = p[parameter] + (sizeof p[parameter]); 324 325 /* No need to copy the trailing '\0' here, but there is no guarantee 326 * that parm[] has been initialized, so there is no guarantee of a 327 * trailing '\0': 328 */ 329 while (i<(sizeof msg)-1 && *parm != '\0' && parm < pend) 330 msg[i++] = *parm++; 331 332 /* Consume the parameter digit too: */ 333 ++message; 334 continue; 335 } 336 337 /* else not a parameter and there is a character after the @ sign; just 338 * copy that. This is known not to be '\0' because of the test above. 339 */ 340 } 341 342 /* At this point *message can't be '\0', even in the bad parameter case 343 * above where there is a lone '@' at the end of the message string. 344 */ 345 msg[i++] = *message++; 346 } 347 348 /* i is always less than (sizeof msg), so: */ 349 msg[i] = '\0'; 350 351 /* And this is the formatted message. It may be larger than 352 * PNG_MAX_ERROR_TEXT, but that is only used for 'chunk' errors and these 353 * are not (currently) formatted. 354 */ 355 png_warning(png_ptr, msg); 356 } 357 #endif /* PNG_WARNINGS_SUPPORTED */ 358 359 #ifdef PNG_BENIGN_ERRORS_SUPPORTED 360 void PNGAPI 361 png_benign_error(png_const_structrp png_ptr, png_const_charp error_message) 362 { 363 if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN) 364 { 365 # ifdef PNG_READ_SUPPORTED 366 if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 && 367 png_ptr->chunk_name != 0) 368 png_chunk_warning(png_ptr, error_message); 369 else 370 # endif 371 png_warning(png_ptr, error_message); 372 } 373 374 else 375 { 376 # ifdef PNG_READ_SUPPORTED 377 if ((png_ptr->mode & PNG_IS_READ_STRUCT) != 0 && 378 png_ptr->chunk_name != 0) 379 png_chunk_error(png_ptr, error_message); 380 else 381 # endif 382 png_error(png_ptr, error_message); 383 } 384 } 385 386 void /* PRIVATE */ 387 png_app_warning(png_const_structrp png_ptr, png_const_charp error_message) 388 { 389 if (png_ptr->flags & PNG_FLAG_APP_WARNINGS_WARN) 390 png_warning(png_ptr, error_message); 391 else 392 png_error(png_ptr, error_message); 393 } 394 395 void /* PRIVATE */ 396 png_app_error(png_const_structrp png_ptr, png_const_charp error_message) 397 { 398 if (png_ptr->flags & PNG_FLAG_APP_ERRORS_WARN) 399 png_warning(png_ptr, error_message); 400 else 401 png_error(png_ptr, error_message); 402 } 403 #endif /* BENIGN_ERRORS */ 404 405 /* These utilities are used internally to build an error message that relates 406 * to the current chunk. The chunk name comes from png_ptr->chunk_name, 407 * this is used to prefix the message. The message is limited in length 408 * to 63 bytes, the name characters are output as hex digits wrapped in [] 409 * if the character is invalid. 410 */ 411 #define isnonalpha(c) ((c) < 65 || (c) > 122 || ((c) > 90 && (c) < 97)) 412 static PNG_CONST char png_digit[16] = { 413 '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 414 'A', 'B', 'C', 'D', 'E', 'F' 415 }; 416 417 #define PNG_MAX_ERROR_TEXT 196 /* Currently limited be profile_error in png.c */ 418 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_ERROR_TEXT_SUPPORTED) 419 static void /* PRIVATE */ 420 png_format_buffer(png_const_structrp png_ptr, png_charp buffer, png_const_charp 421 error_message) 422 { 423 png_uint_32 chunk_name = png_ptr->chunk_name; 424 int iout = 0, ishift = 24; 425 426 while (ishift >= 0) 427 { 428 int c = (int)(chunk_name >> ishift) & 0xff; 429 430 ishift -= 8; 431 if (isnonalpha(c)) 432 { 433 buffer[iout++] = PNG_LITERAL_LEFT_SQUARE_BRACKET; 434 buffer[iout++] = png_digit[(c & 0xf0) >> 4]; 435 buffer[iout++] = png_digit[c & 0x0f]; 436 buffer[iout++] = PNG_LITERAL_RIGHT_SQUARE_BRACKET; 437 } 438 439 else 440 { 441 buffer[iout++] = (char)c; 442 } 443 } 444 445 if (error_message == NULL) 446 buffer[iout] = '\0'; 447 448 else 449 { 450 int iin = 0; 451 452 buffer[iout++] = ':'; 453 buffer[iout++] = ' '; 454 455 while (iin < PNG_MAX_ERROR_TEXT-1 && error_message[iin] != '\0') 456 buffer[iout++] = error_message[iin++]; 457 458 /* iin < PNG_MAX_ERROR_TEXT, so the following is safe: */ 459 buffer[iout] = '\0'; 460 } 461 } 462 #endif /* PNG_WARNINGS_SUPPORTED || PNG_ERROR_TEXT_SUPPORTED */ 463 464 #if defined(PNG_READ_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED) 465 PNG_FUNCTION(void,PNGAPI 466 png_chunk_error,(png_const_structrp png_ptr, png_const_charp error_message), 467 PNG_NORETURN) 468 { 469 char msg[18+PNG_MAX_ERROR_TEXT]; 470 if (png_ptr == NULL) 471 png_error(png_ptr, error_message); 472 473 else 474 { 475 png_format_buffer(png_ptr, msg, error_message); 476 png_error(png_ptr, msg); 477 } 478 } 479 #endif /* PNG_READ_SUPPORTED && PNG_ERROR_TEXT_SUPPORTED */ 480 481 #ifdef PNG_WARNINGS_SUPPORTED 482 void PNGAPI 483 png_chunk_warning(png_const_structrp png_ptr, png_const_charp warning_message) 484 { 485 char msg[18+PNG_MAX_ERROR_TEXT]; 486 if (png_ptr == NULL) 487 png_warning(png_ptr, warning_message); 488 489 else 490 { 491 png_format_buffer(png_ptr, msg, warning_message); 492 png_warning(png_ptr, msg); 493 } 494 } 495 #endif /* PNG_WARNINGS_SUPPORTED */ 496 497 #ifdef PNG_READ_SUPPORTED 498 #ifdef PNG_BENIGN_ERRORS_SUPPORTED 499 void PNGAPI 500 png_chunk_benign_error(png_const_structrp png_ptr, png_const_charp 501 error_message) 502 { 503 if (png_ptr->flags & PNG_FLAG_BENIGN_ERRORS_WARN) 504 png_chunk_warning(png_ptr, error_message); 505 506 else 507 png_chunk_error(png_ptr, error_message); 508 } 509 #endif 510 #endif /* PNG_READ_SUPPORTED */ 511 512 void /* PRIVATE */ 513 png_chunk_report(png_const_structrp png_ptr, png_const_charp message, int error) 514 { 515 /* This is always supported, but for just read or just write it 516 * unconditionally does the right thing. 517 */ 518 # if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED) 519 if (png_ptr->mode & PNG_IS_READ_STRUCT) 520 # endif 521 522 # ifdef PNG_READ_SUPPORTED 523 { 524 if (error < PNG_CHUNK_ERROR) 525 png_chunk_warning(png_ptr, message); 526 527 else 528 png_chunk_benign_error(png_ptr, message); 529 } 530 # endif 531 532 # if defined(PNG_READ_SUPPORTED) && defined(PNG_WRITE_SUPPORTED) 533 else if (!(png_ptr->mode & PNG_IS_READ_STRUCT)) 534 # endif 535 536 # ifdef PNG_WRITE_SUPPORTED 537 { 538 if (error < PNG_CHUNK_WRITE_ERROR) 539 png_app_warning(png_ptr, message); 540 541 else 542 png_app_error(png_ptr, message); 543 } 544 # endif 545 } 546 547 #ifdef PNG_ERROR_TEXT_SUPPORTED 548 #ifdef PNG_FLOATING_POINT_SUPPORTED 549 PNG_FUNCTION(void, 550 png_fixed_error,(png_const_structrp png_ptr, png_const_charp name),PNG_NORETURN) 551 { 552 # define fixed_message "fixed point overflow in " 553 # define fixed_message_ln ((sizeof fixed_message)-1) 554 int iin; 555 char msg[fixed_message_ln+PNG_MAX_ERROR_TEXT]; 556 memcpy(msg, fixed_message, fixed_message_ln); 557 iin = 0; 558 if (name != NULL) while (iin < (PNG_MAX_ERROR_TEXT-1) && name[iin] != 0) 559 { 560 msg[fixed_message_ln + iin] = name[iin]; 561 ++iin; 562 } 563 msg[fixed_message_ln + iin] = 0; 564 png_error(png_ptr, msg); 565 } 566 #endif 567 #endif 568 569 #ifdef PNG_SETJMP_SUPPORTED 570 /* This API only exists if ANSI-C style error handling is used, 571 * otherwise it is necessary for png_default_error to be overridden. 572 */ 573 jmp_buf* PNGAPI 574 png_set_longjmp_fn(png_structrp png_ptr, png_longjmp_ptr longjmp_fn, 575 size_t jmp_buf_size) 576 { 577 /* From libpng 1.6.0 the app gets one chance to set a 'jmpbuf_size' value 578 * and it must not change after that. Libpng doesn't care how big the 579 * buffer is, just that it doesn't change. 580 * 581 * If the buffer size is no *larger* than the size of jmp_buf when libpng is 582 * compiled a built in jmp_buf is returned; this preserves the pre-1.6.0 583 * semantics that this call will not fail. If the size is larger, however, 584 * the buffer is allocated and this may fail, causing the function to return 585 * NULL. 586 */ 587 if (png_ptr == NULL) 588 return NULL; 589 590 if (png_ptr->jmp_buf_ptr == NULL) 591 { 592 png_ptr->jmp_buf_size = 0; /* not allocated */ 593 594 if (jmp_buf_size <= (sizeof png_ptr->jmp_buf_local)) 595 png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local; 596 597 else 598 { 599 png_ptr->jmp_buf_ptr = png_voidcast(jmp_buf *, 600 png_malloc_warn(png_ptr, jmp_buf_size)); 601 602 if (png_ptr->jmp_buf_ptr == NULL) 603 return NULL; /* new NULL return on OOM */ 604 605 png_ptr->jmp_buf_size = jmp_buf_size; 606 } 607 } 608 609 else /* Already allocated: check the size */ 610 { 611 size_t size = png_ptr->jmp_buf_size; 612 613 if (size == 0) 614 { 615 size = (sizeof png_ptr->jmp_buf_local); 616 if (png_ptr->jmp_buf_ptr != &png_ptr->jmp_buf_local) 617 { 618 /* This is an internal error in libpng: somehow we have been left 619 * with a stack allocated jmp_buf when the application regained 620 * control. It's always possible to fix this up, but for the moment 621 * this is a png_error because that makes it easy to detect. 622 */ 623 png_error(png_ptr, "Libpng jmp_buf still allocated"); 624 /* png_ptr->jmp_buf_ptr = &png_ptr->jmp_buf_local; */ 625 } 626 } 627 628 if (size != jmp_buf_size) 629 { 630 png_warning(png_ptr, "Application jmp_buf size changed"); 631 return NULL; /* caller will probably crash: no choice here */ 632 } 633 } 634 635 /* Finally fill in the function, now we have a satisfactory buffer. It is 636 * valid to change the function on every call. 637 */ 638 png_ptr->longjmp_fn = longjmp_fn; 639 return png_ptr->jmp_buf_ptr; 640 } 641 642 void /* PRIVATE */ 643 png_free_jmpbuf(png_structrp png_ptr) 644 { 645 if (png_ptr != NULL) 646 { 647 jmp_buf *jb = png_ptr->jmp_buf_ptr; 648 649 /* A size of 0 is used to indicate a local, stack, allocation of the 650 * pointer; used here and in png.c 651 */ 652 if (jb != NULL && png_ptr->jmp_buf_size > 0) 653 { 654 655 /* This stuff is so that a failure to free the error control structure 656 * does not leave libpng in a state with no valid error handling: the 657 * free always succeeds, if there is an error it gets ignored. 658 */ 659 if (jb != &png_ptr->jmp_buf_local) 660 { 661 /* Make an internal, libpng, jmp_buf to return here */ 662 jmp_buf free_jmp_buf; 663 664 if (!setjmp(free_jmp_buf)) 665 { 666 png_ptr->jmp_buf_ptr = &free_jmp_buf; /* come back here */ 667 png_ptr->jmp_buf_size = 0; /* stack allocation */ 668 png_ptr->longjmp_fn = longjmp; 669 png_free(png_ptr, jb); /* Return to setjmp on error */ 670 } 671 } 672 } 673 674 /* *Always* cancel everything out: */ 675 png_ptr->jmp_buf_size = 0; 676 png_ptr->jmp_buf_ptr = NULL; 677 png_ptr->longjmp_fn = 0; 678 } 679 } 680 #endif 681 682 /* This is the default error handling function. Note that replacements for 683 * this function MUST NOT RETURN, or the program will likely crash. This 684 * function is used by default, or if the program supplies NULL for the 685 * error function pointer in png_set_error_fn(). 686 */ 687 static PNG_FUNCTION(void /* PRIVATE */, 688 png_default_error,(png_const_structrp png_ptr, png_const_charp error_message), 689 PNG_NORETURN) 690 { 691 #ifdef PNG_CONSOLE_IO_SUPPORTED 692 #ifdef PNG_ERROR_NUMBERS_SUPPORTED 693 /* Check on NULL only added in 1.5.4 */ 694 if (error_message != NULL && *error_message == PNG_LITERAL_SHARP) 695 { 696 /* Strip "#nnnn " from beginning of error message. */ 697 int offset; 698 char error_number[16]; 699 for (offset = 0; offset<15; offset++) 700 { 701 error_number[offset] = error_message[offset + 1]; 702 if (error_message[offset] == ' ') 703 break; 704 } 705 706 if ((offset > 1) && (offset < 15)) 707 { 708 error_number[offset - 1] = '\0'; 709 fprintf(stderr, "libpng error no. %s: %s", 710 error_number, error_message + offset + 1); 711 fprintf(stderr, PNG_STRING_NEWLINE); 712 } 713 714 else 715 { 716 fprintf(stderr, "libpng error: %s, offset=%d", 717 error_message, offset); 718 fprintf(stderr, PNG_STRING_NEWLINE); 719 } 720 } 721 else 722 #endif 723 { 724 fprintf(stderr, "libpng error: %s", error_message ? error_message : 725 "undefined"); 726 fprintf(stderr, PNG_STRING_NEWLINE); 727 } 728 #else 729 PNG_UNUSED(error_message) /* Make compiler happy */ 730 #endif 731 png_longjmp(png_ptr, 1); 732 } 733 734 PNG_FUNCTION(void,PNGAPI 735 png_longjmp,(png_const_structrp png_ptr, int val),PNG_NORETURN) 736 { 737 #ifdef PNG_SETJMP_SUPPORTED 738 if (png_ptr && png_ptr->longjmp_fn && png_ptr->jmp_buf_ptr) 739 png_ptr->longjmp_fn(*png_ptr->jmp_buf_ptr, val); 740 #endif 741 742 /* Here if not setjmp support or if png_ptr is null. */ 743 PNG_ABORT(); 744 } 745 746 #ifdef PNG_WARNINGS_SUPPORTED 747 /* This function is called when there is a warning, but the library thinks 748 * it can continue anyway. Replacement functions don't have to do anything 749 * here if you don't want them to. In the default configuration, png_ptr is 750 * not used, but it is passed in case it may be useful. 751 */ 752 static void /* PRIVATE */ 753 png_default_warning(png_const_structrp png_ptr, png_const_charp warning_message) 754 { 755 #ifdef PNG_CONSOLE_IO_SUPPORTED 756 # ifdef PNG_ERROR_NUMBERS_SUPPORTED 757 if (*warning_message == PNG_LITERAL_SHARP) 758 { 759 int offset; 760 char warning_number[16]; 761 for (offset = 0; offset < 15; offset++) 762 { 763 warning_number[offset] = warning_message[offset + 1]; 764 if (warning_message[offset] == ' ') 765 break; 766 } 767 768 if ((offset > 1) && (offset < 15)) 769 { 770 warning_number[offset + 1] = '\0'; 771 fprintf(stderr, "libpng warning no. %s: %s", 772 warning_number, warning_message + offset); 773 fprintf(stderr, PNG_STRING_NEWLINE); 774 } 775 776 else 777 { 778 fprintf(stderr, "libpng warning: %s", 779 warning_message); 780 fprintf(stderr, PNG_STRING_NEWLINE); 781 } 782 } 783 else 784 # endif 785 786 { 787 fprintf(stderr, "libpng warning: %s", warning_message); 788 fprintf(stderr, PNG_STRING_NEWLINE); 789 } 790 #else 791 PNG_UNUSED(warning_message) /* Make compiler happy */ 792 #endif 793 PNG_UNUSED(png_ptr) /* Make compiler happy */ 794 } 795 #endif /* PNG_WARNINGS_SUPPORTED */ 796 797 /* This function is called when the application wants to use another method 798 * of handling errors and warnings. Note that the error function MUST NOT 799 * return to the calling routine or serious problems will occur. The return 800 * method used in the default routine calls longjmp(png_ptr->jmp_buf_ptr, 1) 801 */ 802 void PNGAPI 803 png_set_error_fn(png_structrp png_ptr, png_voidp error_ptr, 804 png_error_ptr error_fn, png_error_ptr warning_fn) 805 { 806 if (png_ptr == NULL) 807 return; 808 809 png_ptr->error_ptr = error_ptr; 810 png_ptr->error_fn = error_fn; 811 #ifdef PNG_WARNINGS_SUPPORTED 812 png_ptr->warning_fn = warning_fn; 813 #else 814 PNG_UNUSED(warning_fn) 815 #endif 816 } 817 818 819 /* This function returns a pointer to the error_ptr associated with the user 820 * functions. The application should free any memory associated with this 821 * pointer before png_write_destroy and png_read_destroy are called. 822 */ 823 png_voidp PNGAPI 824 png_get_error_ptr(png_const_structrp png_ptr) 825 { 826 if (png_ptr == NULL) 827 return NULL; 828 829 return ((png_voidp)png_ptr->error_ptr); 830 } 831 832 833 #ifdef PNG_ERROR_NUMBERS_SUPPORTED 834 void PNGAPI 835 png_set_strip_error_numbers(png_structrp png_ptr, png_uint_32 strip_mode) 836 { 837 if (png_ptr != NULL) 838 { 839 png_ptr->flags &= 840 ((~(PNG_FLAG_STRIP_ERROR_NUMBERS | 841 PNG_FLAG_STRIP_ERROR_TEXT))&strip_mode); 842 } 843 } 844 #endif 845 846 #if defined(PNG_SIMPLIFIED_READ_SUPPORTED) ||\ 847 defined(PNG_SIMPLIFIED_WRITE_SUPPORTED) 848 /* Currently the above both depend on SETJMP_SUPPORTED, however it would be 849 * possible to implement without setjmp support just so long as there is some 850 * way to handle the error return here: 851 */ 852 PNG_FUNCTION(void /* PRIVATE */, 853 png_safe_error,(png_structp png_nonconst_ptr, png_const_charp error_message), 854 PNG_NORETURN) 855 { 856 const png_const_structrp png_ptr = png_nonconst_ptr; 857 png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr); 858 859 /* An error is always logged here, overwriting anything (typically a warning) 860 * that is already there: 861 */ 862 if (image != NULL) 863 { 864 png_safecat(image->message, (sizeof image->message), 0, error_message); 865 image->warning_or_error |= PNG_IMAGE_ERROR; 866 867 /* Retrieve the jmp_buf from within the png_control, making this work for 868 * C++ compilation too is pretty tricky: C++ wants a pointer to the first 869 * element of a jmp_buf, but C doesn't tell us the type of that. 870 */ 871 if (image->opaque != NULL && image->opaque->error_buf != NULL) 872 longjmp(png_control_jmp_buf(image->opaque), 1); 873 874 /* Missing longjmp buffer, the following is to help debugging: */ 875 { 876 size_t pos = png_safecat(image->message, (sizeof image->message), 0, 877 "bad longjmp: "); 878 png_safecat(image->message, (sizeof image->message), pos, 879 error_message); 880 } 881 } 882 883 /* Here on an internal programming error. */ 884 abort(); 885 } 886 887 #ifdef PNG_WARNINGS_SUPPORTED 888 void /* PRIVATE */ 889 png_safe_warning(png_structp png_nonconst_ptr, png_const_charp warning_message) 890 { 891 const png_const_structrp png_ptr = png_nonconst_ptr; 892 png_imagep image = png_voidcast(png_imagep, png_ptr->error_ptr); 893 894 /* A warning is only logged if there is no prior warning or error. */ 895 if (image->warning_or_error == 0) 896 { 897 png_safecat(image->message, (sizeof image->message), 0, warning_message); 898 image->warning_or_error |= PNG_IMAGE_WARNING; 899 } 900 } 901 #endif 902 903 int /* PRIVATE */ 904 png_safe_execute(png_imagep image_in, int (*function)(png_voidp), png_voidp arg) 905 { 906 volatile png_imagep image = image_in; 907 volatile int result; 908 volatile png_voidp saved_error_buf; 909 jmp_buf safe_jmpbuf; 910 911 /* Safely execute function(arg) with png_error returning to this function. */ 912 saved_error_buf = image->opaque->error_buf; 913 result = setjmp(safe_jmpbuf) == 0; 914 915 if (result) 916 { 917 918 image->opaque->error_buf = safe_jmpbuf; 919 result = function(arg); 920 } 921 922 image->opaque->error_buf = saved_error_buf; 923 924 /* And do the cleanup prior to any failure return. */ 925 if (!result) 926 png_image_free(image); 927 928 return result; 929 } 930 #endif /* SIMPLIFIED READ/WRITE */ 931 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */ 932